• Korean Journal of Microbiology
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• v.38 no.3
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• pp.192-197
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• 2002

Fluorescent in situ hybridization (FISH) with rRNA-targeted oligonucleotide probes was used to compare the community structures of free-living and aggregated bacteria at thawing period in Lake Baikal. Targeted groups were Eubacteria, $\alpha$-, $\beta$-, $\gamma$- proteobacteria groups, Cytophaga-Flavobacterium group and Planctomycetales. Total bacterial numbers of free-living bacteria were ranged from $0.2{\times}10^6\cells{\cdot}ml^-1$ to $3.2{\times}10^6\cells{\cdot}ml^-1$, which were decreasing with depth, while the aggregated bacterial numbers were dramatically increasing from $0.4{\times}10^4 to 3.3{\times}10^4 \cells{\cdot}ml^-1$ with depth. The ratios of EUB probe binding cells to DAPI counts were ranged from 52.3 to 74.1% in free-living bacteria, and from 39.6 to 66.7% in the aggregated bacteria, respectively. Community structures of the aggregated bacteria were very different from each free-living bacteria at every depth. At 25 m depth, where the chlorophyll a concentration was highest, both structures were quite different from those of surface layers, rendering the fact that the community structures might be affected by phytoplankton. The vertical profile of community structure of aggregated bacteria is particular. The proportion of $\beta$-proteobacteria group was increasing with depth and it was 51.8% at 100 m, but the dominant group was $\gamma$-pro-teobacteria group at 250 m. Taken together, the biodiversity and succession of aggregated bacteria are quite different from free-living bacteria.

• Journal of Microbiology and Biotechnology
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• v.27 no.12
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• pp.2112-2118
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• 2017

Leuconostoc mesenteroides is used as a starter to produce high-quality kimchi products. In this study, an efficient and economical cabbage juice medium (CJM) was developed by process optimization of cabbage extraction and pasteurization and by compositional supplementation of various lacking nutrients. The pasteurized cabbage juice was determined to be a good medium candidate to cultivate L. mesenteroides, showing maximal cell numbers ($9.85{\times}10^8CFU/ml$) after 24 h. Addition of sucrose and yeast extract with soy peptone resulted in increment of bacterial cell counts in CJM, showing the supplementing effect of the lacking nutrients. Furthermore, addition of shell powder gave a protective effect on bacterial cells by preventing pH decline and organic acid accumulation in CJM, resulting in a 2-fold increase of bacterial counts. The optimized composition of CJM was 70% cabbage juice diluted with water, 0.5% (w/v) sucrose, 1% (w/v) yeast extract, 1% (w/v) soy peptone, and 1.5% (w/v) ark shell powder. The CJM developed in this study was able to yield a comparable level of bacterial counts with MRS medium and reduced the cost by almost 10-fold.

• The Korea Journal of Herbology
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• v.22 no.4
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• pp.287-300
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• 2007

Objectives : The genotoxicity of extract of "Hyeonggaeyeongyotang", a polyherbal formula has been used as a tonic agents in oriental medicine was tested. Methods : Extract of "Hyeonggaeyeongyotang" was tested by In Vitro Chromosome Aberration Test, Bacterial Reverse Mutation Assay and Micronucleus test according to OECD Guidelines and KFDA Guidelines [2005-60]. Results : The obtained results were as follows: 1. Chromosome Aberration Test: No significant changes in the number of aberrant metaphases having structural and number of aberrations were detected in all concentrations of "Hyeonggaeyeongyotang" extracts treated in this study. 2. Bacterial Reverse Mutation Assay: No significant increases in the number of revertant colonies compared to its negative control were detected in all concentrations of "Hyeonggaeyeongyotang" extracts treated in this study against all 5 strains except for $50{\mu}g/ml$ treated group where significantly decreases in colony numbers were detected agains all five strains used in this study as pharmacological effects not genotoxicity. 3. Micronucleus test: No significant changes in the number of micronucleated polychromatic erythrocytes among 2000 polychromatic erythrocytes compared to negative control were detected in all "Hyeonggaeyeongyotang" extracts-dosing groups tested. Conclusions : From above-mentioned results, it is concluded that "Hyeonggaeyeongyotang" extracts have not any genotoxicity against In Vitro Chromosome Aberration Test, Bacterial Reverse Mutation Assay and Micronucleus test.

• Journal of Microbiology and Biotechnology
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• v.27 no.3
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• pp.500-506
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• 2017

To investigate the potential applications of bacterial heme, aminolevulinic acid synthase (HemA) was expressed in a Corynebacterium glutamicum HA strain that had been adaptively evolved against oxidative stress. The red pigment from the constructed strain was extracted and it exhibited the typical heme absorbance at 408 nm from the spectrum. To investigate the potential of this strain as an iron additive for swine, a prototype feed additive was manufactured in pilot scale by culturing the strain in a 5 ton fermenter followed by spray-drying the biomass with flour as an excipient (biomass: flour = 1:10 (w/w)). The 10% prototype additive along with regular feed was supplied to a pig, resulting in a 1.1 kg greater increase in weight gain with no diarrhea in 3 weeks as compared with that in a control pig that was fed an additive containing only flour. To verify if C. glutamicum-synthesized heme is a potential electron carrier, lactic acid bacteria were cultured under aerobic conditions with the extracted heme. The biomasses of the aerobically grown Lactococcus lactis, Lactobacillus rhamosus, and Lactobacillus casei were 97%, 15%, and 4% greater, respectively, than those under fermentative growth conditions. As a potential preservative, cultures of the four strains of lactic acid bacteria were stored at $4^{\circ}C$ with the extracted heme and living lactic acid bacterial cells were counted. There were more L. lactis and L. plantarum live cells when stored with heme, whereas L. rhamosus and L. casei showed no significant differences in live-cell numbers. The potential uses of the heme from C. glutamicum are further discussed.

• Korean Journal of Microbiology
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• v.26 no.4
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• pp.332-338
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• 1988

The density of heterotrophic bacterial population and heterotrophic activity were measured at monthly interval from March, 1986 to March, 1987 at four sites in the Sudong Stream, a tributary of North Han River. Total bacterial numbers and maximum uptake velocity ($V_{max}$) of glucose ranged as 0.8-$25.2\times 10^{5}$ cells/ml, 0.0006-24.39.$\mu$gC/1/hr, respectively. $V_{max}$ of glucose showed marked seasonal periodicity, with highest values in summer. But density of viable bacteria varied considerably, with no definite seasonal pattern. At the nucontaminated site which located in upstream, heterotrophic bacterial population and activities were relatively low, and small variations were observed downstream flowing except the site where animal originated sewage inputs occurred. And this large input of allochthonous materials and bacteria was an important factor for the stream condition.

• Journal of Microbiology and Biotechnology
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• v.25 no.8
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• pp.1299-1306
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• 2015

This study aims to investigate the mechanism of action of the cinnamon bark essential oil (CB), when used singly and also in combination with piperacillin, for its antimicrobial and synergistic activity against beta-lactamase TEM-1 plasmid-conferred Escherichia coli J53 R1. Viable count of bacteria for this combination of essential oil and antibiotic showed a complete killing profile at 20 h and further confirmed its synergistic effect by reducing the bacteria cell numbers. Analysis on the stability of treated cultures for cell membrane permeability by CB when tested against sodium dodecyl sulfate revealed that the bacterial cell membrane was disrupted by the essential oil. Scanning electron microscopy observation and bacterial surface charge measurement also revealed that CB causes irreversible membrane damage and reduces the bacterial surface charge. In addition, bioluminescence expression of Escherichia coli [pSB1075] and E. coli [pSB401] by CB showed reduction, indicating the possibility of the presence of quorum sensing (QS) inhibitors. Gas-chromatography and mass spectrometry of the essential oil of Cinnamomum verum showed that trans-cinnamaldehyde (72.81%), benzyl alcohol (12.5%), and eugenol (6.57%) were the major components in the essential oil. From this study, CB has the potential to reverse E. coli J53 R1 resistance to piperacillin through two pathways; modification in the permeability of the outer membrane or bacterial QS inhibition.

• Reproductive and Developmental Biology
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• v.37 no.4
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• pp.213-217
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• 2013

The objective of this study was to investigate the effect of bacterial contamination on elapsed time after preservation on boar semen. Known numbers of Escherichia coli (E. coli) were inoculated to freshly ejaculated semen and sperm parameters such as viability, motility, agglutination, acrosome integrity and hypo-osmotic swelling test were performed during 7 days of liquid preservation. Semen samples were prepared using antibiotic free BTS extender and 4 different levels of E. coli were treated to semen with following concentrations; 3,000, 5,000, 7,000, 10,000 CFU/ml of sperms. Semen samples were preserved at $17^{\circ}C$ for 7 days in semen storage until analyzed. Aliquots were subjected to measure the sperm viability, motility and agglutination using computer assisted sperm analysis (CASA) system, acrosome integrity was performed using chlortetracycline (CTC) staining method and hypo-osmotic swelling test was performed using hypotonic solution from day 1 (day of semen collection) to 7. Detrimental effects on sperm motility and viability were observed 3 days after preservation at the level of 5,000 CFU/ml (p<0.05). Percentage of sperm abnormality was higher (p<0.05) in over 5,000 CFU/ml groups. Sperm agglutination rate was also significantly higher (p<0.05) in groups of 5,000 and 7,000 CFU/ml. The rate of acrosome reacted sperm was higher as preservation time goes in all the samples but the pattern was clearly higher among E. coli contaminated groups (p<0.05). The sperm membrane integrity in terms of hypo-osmotic test, E. coli affects little compared to other sperm parameters. The deleterious effects observed due to the bacterial contamination in semen suggest that importance of hygiene protocol to minimize the bacterial contamination during semen collection and processing.

• Animal cells and systems
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• v.3 no.2
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• pp.153-159
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• 1999

In an artificial pH-gradient batch culture system, the effects of acidification on the species composition of a heterotrophic bacterial community were analyzed. As a result of this study, it was found that total bacteria numbers were not affected by acidification and that the population of hetero-trophic bacteria decreased as pH became lower. The heterotrophic bacteria isolated from the entire pH gradient were 12 genera and 22 species. Among them, 64% were gram negative and 36% were gram positive bacteria. As pH decreased, the distribution rate of gram negative bacteria increased while that of gram positive bacteria decreased. The diversity of genera decreased from 13 to 5 as pH decreased from 7 to 3. The G+C content of all of the 202 isolated strains varied from 22.8 to 77.0%, and increased in interspecies of same genus as pH decreased. As a result of clustering analysis, the diversity index of species ranged from 1.13 to 2.37, and it had lower indices as pH decreased. In order to evaluate the diversity of numbers of sample of different size, a rarefaction method was used to analyze the expected number of species appearance according to pH. The statistical significance of species diversity was verified by the fact that the number decreased at lower pH.

• Journal of Nutrition and Health
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• v.32 no.1
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• pp.64-64
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• 1999

The relations between micorfloral compositions and environmental factors of 32 Korean infants were sought through statistical analysis after examination of fecal bacterial and questions to their mothers about feeding experiences at three different times for each subjects, about one week after birth, before weaning (2-3 months after birth), and after weaning 95-7 months after birth). The majority of mothers fed their infants cereal foods after the age of 4 months and began weaning with fruit juice and commercial weaning foods. Defection frequencies and fecal pH of infants decreased significantly during the examination period and 37.5% of total infants in fecal samples increased significantly during the examination period, which means that the kinds of bacterial genera increase with aging of infants. Frequencies of streptococci were significantly higher in infants fed delivered by Caesarian section than infants delivered naturally. Frequencies of clostridia were significantly higher in infants fed with cereal food before 4 months of age than after 5 months. The infants fed with probiotics showed significantly higher frequencies of veillonella at about 1 week old. They also showed significantly higher frequencies of clostridia before weaning than the infant fed with no probiotics, but significantly lower frequencies of C. perfringens before weaning. The infants fed with probiotics showed significantly higher number of streptococci at the age of about 1 week and significantly higher numbers of total aerobes before weaning, but significantly lower numbers of bacteroides after weaning than their counter parts. The fecal pH was directly proportional to the number of clostridia, klebsiella, and total aerobes at about 1 week after birth, to the number of E. coli before weaning, and to the number of streptococci and clostridia after weaning. Fecal pH had a negative relationship to the total number of anaerobes in 1-week-old infants. The infants that had diarrhea during lactation showed higher frequencies of bacteroides before weaning than those that didn't.

• Journal of Nutrition and Health
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• v.32 no.1
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• pp.67-74
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• 1999

The relations between micorfloral compositions and environmental factors of 32 Korean infants were sought through statistical analysis after examinaton of fecal bacterial and questions to their mothers about feeding experiences at three different times for each subjects, about one week after birth, before weaning (2-3 months after birth), and after weaning 95-7 months after birth). The majority of mothers fed their infants cereal foods after the age of 4 months and began weaning with fruit juice and commercial weaning foods. Defection frequencies and fecal pH of infants decreased significantly during the examination period and 37.5% of total infants in fecal samples increased significantly during the examination period, which means that the kinds of bacterial genera increase with aging of infants. Frequencies of streptococci were significantly higher in infants fed delivered by Caesarian section than infants delived naturally. Frequencies of clostrida were significantly higher in infants fed with cerealfood before 4 months of age than after 5 months. The infants fed with probiotics showed significantly higher frequencies of veillonella at about 1 week old. They also showed significantly higher frequencies of clostridia before weaning than the infant fed with no probiotics, but significantly lower frequencise of C. perfringens before weaning. The infants fed with probiotics showed significantly higher number of streptococci at the age of about 1 week and significantly higher numbers of total aerobes before weaning, but significantly lower numbers of bacteroides after weaning than their counter parts. The fecla pH was directly proportional to the number of clostridia, klebsiella, and total aerobes at about 1 week after birth, to the number of E. coli before weaning, and to the number of streptococci and clostridia after weaning. Fecal pH had a negative relationship to the total number of anaerobes in 1-week-old infants. The infants that had diarrhea during lactation showed higher frequencies of bacteroides before weaning than those that didn't.